Survivin is a 16.5 kDa intracellular protein that belongs to the inhibitor of apoptosis protein (IAP) family. Survivin acts in concert with the mitotic spindle apparatus to regulate cell division. It is expressed in certain cells during the G2/M phase of the cell cycle and associates with the spindle microtubule organizing center during this phase of cell cycle progression [Zhao J, et al. (2000) J Cell Sci, 113:4363-71; Li F, et al. (1998) Nature, 396:580-4; Fortugno P, et al. (2002) J Cell Sci, 115:575-85]. Survivin has also been shown to modulate the function of certain caspases, directly inhibiting apoptosis [Tamm I, et al. (1998) Cancer Res, 58:5215-20; Conway et al. (2000) Blood 95:1435-42; Shin S, et al. (2001) Biochemistry, 40:1117-23]. In addition, survivin inhibits the cyclin D/cdk4 complex [Fukuda S, Pelus L M. (2002) Cell Cycle, 1(5):322-6], permitting cell cycle progression. Thus, survivin functions in critical roles at a number of different cellular loci to regulate the cell cycle and to inhibit apoptotic cell death.
Survivin is overexpressed during the G(2)/M phase of the cell cycle in most cancer cells and is one of the most specific cancer antigens identified to date. It is expressed in a large percentage of tumors and is rarely detectable in normal adult tissues [Overwijk W W, et al. (1998) J Exp Med, 188:277-86; Adida C, et al. (1998) Am J Pathol 152:43-49]. Although survivin is expressed in some instances within CD34(+) hematopoietic stem and progenitor cells that have been stimulated by hematopoetic growth factors, it is generally not presented on the surface of these cells. [Fukuda S, Pelus L M. (2002) Cell Cycle. 1(5):322-6].
In addition to many other cancers, survivin expression occurs commonly in malignant gliomas where it is associated with a poor prognosis [Kajiwara Y, et al. (2003) Cancer 97:1077-1083; Sasaki T, (2002) Acta Neuropathol (Berl) 104:105-109; Chakravarti A, et al. (2002) J Clin Oncol, 20:1063-8]. Since survivin is expressed by many different cancer types, and consequently, its use as a tumor vaccine target has broad implications for anticancer vaccine therapy. However, previous studies have not identified survivin peptides that are effective when administered following tumor challenge. Further, little data is available concerning the potential effectiveness of survivin peptides in humans. Therefore, there is an ongoing need for survivin peptides that can elicit strong cellular immune responses for use as anti-survivin cancer immunotherapies.